The mean value theorem states that if $F(x)$ is a differentiable function on the interval $[a, b],$ then there exists some number $c$ between $a$ and $b$ such that
$$F^{\prime}(c)=\frac{F(b)-F(a)}{b-a}$$
Explain why the mean value theorem implies that if a car averages 60 miles per hour in some 10 -minute interval, then the car's instantaneous velocity is 60 miles per hour at least once in that interval.